The disclosures of Japanese Patent Application No. 11-357761 filed on Dec. 16, 1999 and No. 2000-108295 filed on Apr. 10, 2000 including the specification, drawings and abstract are incorporated herein by reference in their entirety.
1. Field of the Invention
This invention relates to a vehicle deceleration control apparatus that gives deceleration to the vehicle and a control method for the same. More particularly, the invention relates to a vehicle deceleration control apparatus that gives deceleration to the vehicle in accordance with operating conditions of the accelerator and a control method for the same.
2. Description of Related Art
One known arrangement relating to this invention is a deceleration control apparatus that gives deceleration to the vehicle by applying a braking force when the driver releases an accelerator pedal from the depressed state. Japanese Patent Application Laid-Open Publication HEI 9-95222, discloses a deceleration control apparaus, in which a braking force is applied to a main brake system when the accelerator pedal is in a deceleration zone.
Equipping a vehicle with such a deceleration control apparatus eliminates the need for the driver to frequently operate the brake pedal when gradually accelerating or decelerating the vehicle, thus enhancing a deceleration response and driving is made easier.
In this known arrangement, deceleration control in consideration of road traffic conditions is not provided. In light traffic conditions, however, it is not particularly necessary to make deceleration greater and a greater deceleration may even give the driver a sense of awkwardness. Under heavy traffic conditions, on the other hand, the driver needs to operate the brake more frequently with a small deceleration, which makes it necessary to augment deceleration for an improved deceleration response.
An object of the invention is to provide a vehicle deceleration control apparatus that is capable of giving appropriate deceleration according to the traffic conditions.
To achieve the foregoing object, a vehicle deceleration control apparatus according to one embodiment of the invention has an arrangement, in which an accelerator operating condition detecting device is used to detect the operating condition of an accelerator and, when it is determined that the accelerator operating condition is in a return operation condition, a deceleration application device is controlled so as to give deceleration to the vehicle. Further, by evaluating the distance from the vehicle ahead, the vehicle deceleration control apparatus controls using the deceleration application device to make deceleration to be given smaller when the distance is greater than when the distance is shorter.
According to the invention, deceleration to be given is controlled by determining the distance from the vehicle ahead and in accordance with the distance from the vehicle ahead. When the distance from the vehicle ahead is long, deceleration is kept to a small rate to prevent an excessive deceleration from being produced. When the distance from the vehicle ahead is short, deceleration is given more amply. This makes it possible to decelerate the vehicle without requiring frequent braking operations and keep an appropriate distance from the vehicle ahead.
This vehicle may be equipped with a vehicle-to-vehicle distance detecting device that detects the distance from the vehicle ahead and the vehicle deceleration control apparatus according to this invention preferably uses this vehicle-to-vehicle distance detecting device to determine the distance from the vehicle ahead. A laser radar, millimeter wave sensor, and a similar device may be appropriately used for the vehicle-to-vehicle distance detecting device such as this one.
In addition, the vehicle may also be provided with a relative speed detecting device that detects a relative speed with respect to the vehicle ahead, and the data representing the vehicle-to-vehicle distance and the relative speed with respect to the vehicle ahead may be used as a basis for adjusting deceleration. If the vehicle ahead runs faster than the driver""s vehicle even with a small distance available between the two vehicles, there is only a little necessity for making deceleration greater.
The distance between the two vehicles may even be evaluated based on fluctuations with time in accelerator operating conditions as detected by the accelerator operating condition detecting device.
The inventor has found that the shorter the distance from the vehicle ahead, the greater are the fluctuations with time in accelerator operating conditions even with the same driver. That is, it is possible to estimate the distance from the vehicle ahead based on the fluctuations with time in accelerator operating conditions. This eliminates the need for providing the vehicle-to-vehicle distance detecting device, thus simplifying the construction of the control device.
It is also preferable that the deceleration to be applied by the deceleration application device be set in accordance with an accelerator operating position detected by the accelerator operating condition detecting device. This allows deceleration to be applied so as to suit the driver""s intention by varying deceleration according to the accelerator operating position.
It is preferable that the deceleration application device applies deceleration by controlling a braking force. If a mechanism that aids in the braking force in proportion to a brake operating force is employed, the invention can be embodied with simple modifications.
An embodiment of this invention is not limited to a vehicle deceleration control apparatus such as that described heretofore. Another embodiment of the invention includes, for example, a vehicle equipped with a vehicle deceleration control apparatus and a control method for the vehicle deceleration control apparatus.